The reproduction of kakapo (Strigops habroptilus) on offshore island refuges was monitored between 1990 and 2002. Productivity was primarily determined by the proportion of females that nested each breeding year. Within the same island, the proportion of females nesting each breeding year ranged between 33 – 95% but, as a proportion of the total female population, was just 5 – 42% between 1990 and 1999. The deliberate placement of the entire adult female population on Codfish Island (Whenua Hou) in anticipation of an exceptional fruit crop resulted in 95% of them nesting in 2002, raising 24 fledglings and increasing the total population by 39%. Although efforts to increase the frequency of kakapo breeding by providing supplementary food have been unsuccessful, nesting and fledging success increased significantly following the introduction of new, more intensive, management methods in 1995. Hatching success has, however, remained poor, with just 42% of eggs hatching. Comparison with related parrot species suggests that the kakapo’s hatching success is unusually low, perhaps because of inbreeding. Despite infrequent breeding and poor hatching success, the kakapo population has increased by 69% from 51 birds in 1995 to 86 in 2002. The female population has increased from 21 birds in 1995 to 41 in 2002, 20 of which are presently less than 10 years old.
Since the last review of kakapo biology, published 50 years ago, much has been learnt as a result of the transfer of all known individuals to offshore islands, and their intensive management to increase adult survival and productivity. This review summarises information on a diversity of topics, including taxonomy, plumage, moult, mass, anatomy, physiology, reasons for decline in distribution, present numbers and status, sex ratio, habitat, home range, foraging activities, diet, voice, breeding biology, nesting success, sexual maturity, and adult survival. In addition, those kakapo attributes that compromise its long-term survival in present-day New Zealand are discussed, along with management practises developed to overcome these problems.
Colony attendance and behaviour of non-breeding Buller’s albatrosses (Thalassarche bulleri) were studied at 2 Snares Is colonies in 2000-2004. Non-breeders comprised 31-32% of birds ashore in Mar-May (incubation to early chick-rearing), 44% in Jul (late chick-rearing), and 51% overall. Among non-breeders, the proportion of adults that had been recorded breeding in previous years decreased from 47% in Mar to 4% in Jul, with prebreeders (known-age birds that had not been observed breeding) dominating the composition overall (80%). The percentage of surviving birds seen ashore was 59% among prebreeders aged 6 years (modal age of first return), 88% among experienced prebreeders (birds that had been recorded ashore in >1 breeding season), 86% among remating (widowed or divorced) adults, and 63% among sabbatical (birds that had been recorded breeding in previous years, but were not breeding in the year of observation) adults. Colony attendance period was shortest among inexperienced prebreeders (latest birds to arrive), longest among 3rd year (i.e. known-age birds recorded ashore for the 3rd year) prebreeders (early arrival, late departure), and intermediate among last-time prebreeders and former breeders (early arrival, departure in mid-season). Failed breeders attended for up to 3 months, but departed after May irrespective of failure date. Birds stayed ashore for longer and at sea for shorter periods as they gained experience; the percentage of days ashore increased up to the 3rd prebreeding year, and was higher in males than females. Movements between colonies and subcolonies were most frequent during the first 3 prebreeding years. Prebreeders frequently joined display groups during their first 2 years (34% of observations in May), and associated with a nest site in May-Jul of their 3rd year. Among remating adults, displaying was most frequent in females and early in the season (Mar); their behaviour converged towards that of paired adults by May. Attendance patterns and behaviour were broadly similar to those of other albatrosses, except for earlier departure during the last prebreeding year not previously reported in an annually breeding species.
Sixteen of 26 hand-reared kakapo chicks (62%) have been successfully returned to the wild. These chicks were initially kept in thermostatically-controlled brooders, then in plastic tubs in an air-conditioned room, and finally a pen in an unheated room prior to transfer to an outdoor pen and release in the wild. Brooding temperature was progressively reduced to simulate the progressively longer period kakapo chicks spend in the nest without brooding. Humidity was maintained at 80% to simulate that measured in kakapo nests. Some chicks fed a relatively high fat diet within their first 20 days after hatching developed fatty liver disease; subsequently, chicks less than 45 days of age were fed a lower fat diet and older chicks gradually converted to a higher fat diet. Normal gut flora was successfully established in chicks by adding small quantities of adult kakapo faeces that had been screened for diseases and parasites. The growth rate of hand-reared chicks was significantly slower than that of parent-reared chicks during the first 40 days after hatching but there was no significant difference in growth rate in older chicks. Half the disparity in the growth rates of hand-reared and parent-reared chicks was due to the fact that most hand-reared chicks were suffering from ill health or injury before being taken into captivity. Two male chicks reared in isolation from other kakapo display varying degrees of sexual attraction to humans. The only sexually mature hand-reared female chick has mated and hatched a chick in the wild. Hand-reared kakapo comprised 40% of all chicks fledged since 1990 and presently comprise 20% of the total population of 86 birds.
Satellite telemetry was used between 1994 and 2004 to identify the distribution of 2 closely-related species of wandering albatross, Gibson’s (Diomedea gibsoni) and Antipodean (D. antipodensis), which breed in the New Zealand subantarctic. Trials of methods of attaching transmitters revealed that harnessed transmitters decreased foraging efficiency and increased mortality, whereas transmitters glued or taped on birds had little effect. There was some overlap in the species foraging ranges, but D. gibsoni mostly foraged in the Tasman Sea and D. antipodensis in the Pacific Ocean east of New Zealand. For both species the range of non-breeding birds was larger than that of breeders, but the core areas used by both breeders and non-breeders were similar. Non-breeding male D. antipodensis had the largest range, foraging off the coast of Chile, Antarctica and in the tropical South Pacific. In comparison, the range of D. gibsoni was small, with non-breeding male and female birds foraging westward to the south-eastern Indian Ocean but avoiding Antarctic waters. Individuals of both species and all stages of maturity had preferred but large foraging areas which lasted many years. Some seasonal trends in distribution were found. Both species preferred to forage at the outer edge of shelves and over seamounts, particularly where there were strong currents or eddies and productivity was enhanced, as well as over deep water. Over the past 40 years, longline fisheries used a minimum 89% and 53% of the range over which our study tracked D. gibsoni and D. antipodensis respectively. Of 18 D. gibsoni and 35 D. antipodensis banded birds recovered dead since 1971, 22% and 83% respectively were related to fisheries. The areas where closures of fisheries would be most likely to reduce bycatch are identified.
Photo essay compiled by Murray Williams from text an photographs provided by Don Merton, with additional photographs from Department of Conservation, Hocken Library and Archives New Zealand.
Breeding of North Island kokako (Callaeas cinerea wilsoni) was studied at Mapara, King Country, New Zealand, from 1990 until 2000. Sixty-seven adult and 167 nestling kokako were colour-banded, and radio-transmitters were attached to 49 to identify individuals and to help locate nests. Pair bonds were stable: 7% of pairs split each year for reasons other than mate death. More than 200 nests were located, which permitted observations of breeding-season length, nesting behaviour, clutch and brood size, incubation and nestling periods, and nest success. The nesting season began in late Oct but varied greatly in duration, lasting from 7 weeks in 1993/94 to 21 weeks in 1994/95. We attributed this variation to changes in abundance of key food fruits. Females made up to 5 breeding attempts and fledged as many as 6 chicks in a season. Male-male pairs also built nests, though the apportioning of effort differed from that of conventional pairs. Mean clutch and brood sizes were 2.31 and 1.96, respectively. The incubation period was 18 days and fledging took a further 34-42 days. Sixty-one percent of nesting attempts successfully fledged young when mammalian pests were controlled, as against 8% when there was no predator control. Predation of eggs and chicks by ship rats (Rattus rattus) and brush-tailed possums (Trichosurus vulpecula) was the main cause of nest failure, whereas deaths of nesting adult females mostly caused be stoats (Mustela erminea). Kokako are well adapted to cope with avian predation, but their future conservation depends on management of key small mammalian pests.
The little information that we have on the breeding ecology of the extinct Stewart Is snipe (Coenocorypha aucklandica iredalei) is based on books published by Herbert Guthrie-Smith and Major Robert Wilson following visits to Big South Cape I in 1923 and 1931 respectively. Wilson was a member of a party including Edgar Stead, who collected 4 clutches of eggs now in Canterbury Museum. We summarise the published information on breeding ecology of the Stewart Is snipe, and provide new information based on previously unpublished photographs of nests, and notes made by members of the 1923 and 1931 visits to Big South Cape I, including Edgar Stead’s unpublished diary. Stewart Is snipe appear to have had a different chick-rearing strategy from all other Coenocorypha snipe, with pairs jointly caring for a single chick. Guthrie-Smith’s 1923 record of courtship-feeding was the 1st reported instance for the entire family Scolopacidae.
The doubly-labelled water technique was used to measure energy expenditure in 20 free-living kakapo (Strigops habroptilus) on Codfish and Little Barrier Islands. Daily energy expenditure (DEE) averaged 799 kj/d, equivalent to 1.4 x BMR (basal metabolic rate), the lowest value recorded for any adult wild bird. DEE was higher in males than females, and was greater on Codfish Island than on Little Barrier Island. Supplementary food taken from hoppers by kakapo supplied about half of their DEE; a few individuals apparently obtained virtually all their energy needs from supplementary food. Use of food from hoppers did not affect energy expenditure directly, but apparently did so via long-term elevation of body mass. Supplementary feeding, particularly of energy-dense items such as nuts and seeds, greatly depressed body-water turnover rates. Some implications of the often high level of supplementary food taken by kakapo are discussed. Adjusting the supplementary feeding programme to meet more precisely the needs of individual birds would probably improve the overall nutrition of the surviving kakapo population.
The kakapo (Strigops habroptilus) is a critically endangered, flightless parrot endemic to New Zealand. In 2002, 24 chicks were raised on Codfish Island (Whenua Hou) to increase the total population by 37% to 86 individuals. Data on hatching and fledging of kakapo chicks allowed comparisons to be made between males and females, and between broods of one and two chicks, in hatching weight, growth, weight at fledging, and age of fledging. There was no significant difference in hatching weight between sexes or brood sizes but males were significantly heavier at 60 days old and at fledging. Chicks from broods of one grew more slowly and fledged earlier at lighter weights than chicks from broods of two. Early fledging of solitary chicks might be in response to a lack of mental and physical stimulation.